In a large non-stick skillet, cook thinly sliced onions, with 1 tbsp.
olive oil and the dried thyme until golden brown, approximately 30 min
utes. Stir occasionally.
Meanwhile preheat the oven to 400. Place the mushrooms on the foil lin
ed sheet try. Lightly brush each mushroom with olive oil.
Place the mushrooms in the oven and roast until fork tender. Remove an
d set aside.
In each mushroom cap spoon in cooked onions top with 1/2 cup of crouto
ns and Swiss cheese.
Return to the oven and bake until cheese is melted.